RSS file not found but loaded by url

I have an error in my RSS feed,

What error?

if I go into my hosting, I can’t find any file named “feed” or similar.

The RSS feed address, like all other WordPress addresses, are virtual URLs dynamically generated by WordPress. There’s no static file sitting on your server to edit.

When I validate with w3 tool appears an error https://validator.w3.org/feed/check.cgi?url=www.fotov60.com%2Ffeed

Sorry
This feed does not validate.

line 3, column 0: XML parsing error: <unknown>:3:0: XML or text declaration not at start of entity [help]

<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"
Source: https://www.fotov60.com/feed
 
 
<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"
xmlns:content="https://purl.org/rss/1.0/modules/content/"
xmlns:wfw="https://wellformedweb.org/CommentAPI/"
xmlns:dc="https://purl.org/dc/elements/1.1/"
xmlns:atom="https://www.w3.org/2005/Atom"
xmlns:sy="https://purl.org/rss/1.0/modules/syndication/"
xmlns:slash="https://purl.org/rss/1.0/modules/slash/"

And I use feedburner to link in my web and you can see there another error https://feeds.feedburner.com/Fotov60

This page contains the following errors:
error on line 3 at column 6: XML declaration allowed only at the start of the document
Below is a rendering of the page up to the first error.

How can I fix this then?

The error in the RSS feed is due to the two blank lines at the top of the XML code.

This problem usually stems from the site’s active theme, and not the WordPress code generating the RSS feed. To confirm what I’m saying, if you view the HTML source on your normal WordPress pages, you’ll see the same two blank lines at the top before the DOCTYPE declaration begins.

The two blank lines are you talking about are this?

view-source:https://www.fotov60.com/

How can I fix it?